Investigation of cell mechanics using single-beam acoustic tweezers as a versatile tool for the diagnosis and treatment of highly invasive breast cancer cell lines: an in vitro study

Advancements in diagnostic systems for metastatic cancer over the last few decades have played a significant role in providing patients with effective treatment by evaluating the characteristics of cancer cells. Despite the progress made in cancer prognosis, we still rely on the visual analysis of tissues or cells from histopathologists, where the subjectivity of traditional manual interpretation persists. This paper presents the development of a dual diagnosis and treatment tool using an in vitro acoustic tweezers platform with a 50MHz ultrasonic transducer for label-free trapping and bursting of human breast cancer cells. For cancer cell detection and classification, the mechanical properties of a single cancer cell were quantified by single-beam acoustic tweezers (SBAT), a noncontact assessment tool using a focused acoustic beam. Cell-mimicking phantoms and agarose hydrogel spheres (AHSs) served to standardize the biomechanical characteristics of the cells. Based on the analytical comparison of deformability levels between the cells and the AHSs, the mechanical properties of the cells could be indirectly measured by interpolating the Young's moduli of the AHSs. As a result, the calculated Young's moduli, i.e., 1.527kPa for MDA-MB-231 (highly invasive breast cancer cells), 2.650kPa for MCF-7 (weakly invasive breast cancer cells), and 2.772kPa for SKBR-3 (weakly invasive breast cancer cells), indicate that highly invasive cancer cells exhibited a lower Young's moduli than weakly invasive cells, which indicates a higher deformability of highly invasive cancer cells, leading to a higher metastasis rate. Single-cell treatment may also be carried out by bursting a highly invasive cell with high-intensity, focused ultrasound. Cancer: An acoustic approach to diagnosis and treatmentA new acoustic technique is able to detect and kill invasive cancer cells. The technology, known as single-beam acoustic tweezers (SBAT), was developed by an international team led by Hyung Ham Kim of Korea's Pohang University of Science and Technology. It uses an ultrasonic beam to trap cells in place and apply force to deform them. The team first calibrated SBAT with agarose gel spheres before using it to measure the deformability of breast cancer cells. The technique was able to distinguish between highly- and weakly-invasive based on their deformability, making it possible to rapidly characterize the metastatic potential of cancer cells. Finally, the researchers showed that a higher frequency beam could be used to burst highly-invasive cancer cells and that the beam could be focused well enough to target a single cell.